Method of replacing at least a portion of a semiconductor substrate deposition chamber liner

ABSTRACT

A method includes removing at least a piece of a deposition chamber liner from a deposition chamber by passing it through a passageway to the deposition chamber through which semiconductor substrates pass into and out of the chamber for deposition processing. A replacement for the removed deposition chamber liner piece is provided into the chamber by passing the replacement through said passageway. A liner apparatus includes a plurality of pieces which when assembled within a selected semiconductor substrate deposition processor chamber are configured to restrict at least a majority portion of all internal wall surfaces which define said semiconductor substrate deposition processor chamber from exposure to deposition material within the chamber. At least some of the pieces are sized for passing completely through a substrates passageway to the chamber through which semiconductor substrates pass into and out of the chamber for deposition processing.

TECHNICAL FIELD

This invention relates to methods of replacing at least a portion of asemiconductor substrate deposition chamber liner, to methods ofdepositing materials over a plurality of semiconductor substrates, andto liners for semiconductor substrate deposition processing chambers.

BACKGROUND OF THE INVENTION

Semiconductor processing in the fabrication of integrated circuitrytypically includes the deposition of layers on semiconductor substrates.Exemplary processes include physical vapor deposition (PVD), andchemical vapor deposition (CVD) including atomic layer deposition (ALD).With typical ALD, successive mono-atomic layers are adsorbed to asubstrate and/or reacted with the outer layer on the substrate,typically by successive feeding of different precursors to the substratesurface.

Chemical and physical vapor depositions can be conducted within chambersor reactors which retain a single substrate upon a wafer holder orsusceptor. The chambers include internal walls which can undesirablyhave deposition product deposited thereupon in addition to thesubstrate. This is particularly problematic in ALD and other CVDprocesses, yet can also occur PVD chambers. One existing method ofprotecting or preserving the internal chamber wall is to shield suchfrom the deposition material with one or more removable liners. Theseliners might be received immediately adjacent or against the internalchamber walls. Alternately, the liners might be displaced therefrom,thereby defining an appreciably reduced volume chamber within which thesubstrate is received for deposition. One advantage of using liners isthat they can be periodically replaced with new or cleaned liners,thereby extending the life of the deposition chambers. Further andregardless, the spent liners can typically be removed and replaced muchmore quickly than the time it would take to clean the internal chamberwalls at a given cleaning interval.

The present method for replacing the liners includes partial disassemblyof the deposition chamber. Specifically, the lid is typically removed toprovide access to the liners for their quick removal and replacementwith fresh liners. The deposition processor is then reassembled for use.The spent liners can thereby be discarded or cleaned for re-use withoutadding to the downtime for the processor for the same. Such methods dohowever expose the entire deposition processor apparatus to clean roomambient conditions, thereby increasing downtime, thermal cycling andpressure cycling of the apparatus. It would be desirable to developmethods and structures that can be used to minimize or eliminate suchdowntime and temperature and pressure cycling.

The invention was motivated in overcoming the above-described drawbacks,although it is in no way so limited. The invention is only limited bythe accompanying claims as literally worded without interpretative orother limiting reference to the specification or drawings, and inaccordance with the doctrine of equivalents.

SUMMARY

The invention includes methods of replacing at least a portion of asemiconductor substrate deposition chamber liner, methods of depositingmaterials over a plurality of semiconductor substrates, andsemiconductor substrate deposition processor chamber liner apparatus. Inone implementation, a method of replacing at least a portion of asemiconductor substrate deposition chamber liner includes removing atleast a piece of a deposition chamber liner from a deposition chamber bypassing it through a passageway to the deposition chamber through whichsemiconductor substrates pass into and out of the chamber for depositionprocessing. A replacement for the removed deposition chamber liner pieceis provided into the chamber by passing the replacement through saidpassageway through which semiconductor substrates pass into and out ofthe chamber for deposition processing.

In one implementation, a semiconductor substrate deposition processorchamber liner apparatus includes a plurality of pieces which whenassembled within a selected semiconductor substrate deposition processorchamber are configured to restrict at least a majority portion of allinternal wall surfaces which define said semiconductor substratedeposition processor chamber from exposure to deposition material withinthe chamber. At least some of the pieces are sized for passingcompletely through a substrate passageway to the chamber through whichsemiconductor substrates pass into and out of the chamber for depositionprocessing.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic top plan view of a cluster processingapparatus.

FIG. 2 is a diagrammatic sectional view of a portion of the apparatus ofFIG. 1 shown in one operational configuration.

FIG. 3 is a diagrammatic sectional view taken through line 3—3 in FIG.2.

FIG. 4 is a diagrammatic sectional view like FIG. 2 but shown in anotheroperational orientation.

FIG. 5 is a diagrammatic sectional, view like FIG. 2 but shown in stillanother operational orientation.

FIG. 6 is a diagrammatic sectional view of a portion of the apparatus ofFIG. 1 shown in one operational configuration.

FIG. 7 is a diagrammatic sectional view like FIG. 6 but shown in anotheroperational configuration.

FIG. 8 is a diagrammatic sectional view like FIG. 6 but shown in stillanother operational configuration.

FIG. 9 is a diagrammatic sectional view like FIG. 6 but shown in afurther operational configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Referring initially to FIG. 1, an exemplary cluster processing apparatusis indicated generally with reference 10. Such includes a subatmospherictransfer chamber 12 having a plurality of substrate processors or loadlock chambers 14 peripherally received thereabout. Load lock chambersare utilized to transfer semiconductor substrates, typicallyindividually, from room ambient to within processor 10 for deposition orother processing within the processing chambers 14. In the context ofthis document, the term “semiconductor substrate” or “semiconductivesubstrate” is defined to mean any construction comprising semiconductivematerial, including, but not limited to, bulk semiconductive materialssuch as a semiconductive wafer (either alone or in assemblies comprisingother materials thereon), and semiconductive material layers (eitheralone or in assemblies comprising other materials). The term “substrate”refers to any supporting structure, including, but not limited to, thesemiconductive substrates described above.

A mechanism 16 is associated with subatmospheric transfer chamber 12 fortransferring the substrates into and out of the respective processors14. FIG. 1 shows mechanism 16 engaging relative to one of processors 14,with FIGS. 2-9 showing sectional diagrammatic depictions of differentoperational configurations associated with the one deposition processor.Of course, the depicted cluster apparatus 10 and processor chambers 14are only exemplary, and merely provide an exemplary environment withinwhich a method in accordance with the invention can be practiced andwithin which a deposition processor chamber liner apparatus can be used.The concluding claims are in no way limited by the environment but forthe literal wording appearing in such claims, and without limiting orinterpretative reference to the specification or drawings, and inaccordance with the doctrine of equivalents.

Referring to FIGS. 1-3, deposition processor 14 includes a semiconductorsubstrate deposition chamber 18 which will be at subatmospheric pressureduring deposition processing. Such includes internal wall surfaces 19.In the depicted example, processor 14 is shown in the form of an ALD orother CVD processor chamber having an exemplary gas inlet 22diagrammatically shown at the top for the injecting of one or moreprecursor gasses to within chamber 18. Showerheads or other gasdispersing devices might also be used.

Subatmospheric deposition chamber 18 is provided in communication withsubatmospheric transfer chamber 12 by or through a passageway 20. Suchis an exemplary passageway through which semiconductor substrates passinto and out of chamber 18 relative to transfer chamber 12 fordeposition processing. One exemplary existing passageway has a maximumheight of 0.75 inch and a maximum width of 8.25 inches. The inventioncontemplates use with deposition chambers having passageways of theserespective size dimensions or lesser of one or both dimensions, as wellas passageways having greater size in one or both dimensions.

Processor 14 includes a movable substrate holder or heater 24. Such isdiagrammatically shown as being supported by a post 26. A mechanism 28is associated with post 26 for raising and lowering substrateheater/support 24. In typical existing processing, an individual waferwould be positioned from subatmospheric transfer chamber 12 throughpassageway 20 and onto wafer heater/support 24 utilizing an extendablearm of mechanism 16. Heater/support 24 typically includes a series ofupwardly projecting and retractable pins upon which the wafer would beinitially placed. The placement arm or paddle of mechanism 16 would thenbe retracted from the deposition chamber through passageway 20. The pinswould be lowered/retracted such that the substrate rests atop thedepicted upper, surface of heater/support 24. Heater/support 24 wouldthen be raised with mechanism 28 to position the wafer more proximatethe showerhead (not shown) at the upper surface of the chamber withwhich inlet 22 communicates. At the conclusion of deposition processing,the process is reversed with the substrate being removed from chamber 18through passageway 20.

The invention of course also contemplates any other deposition chamber,whether existing or yet-to-be developed, including, by way of exampleonly, physical vapor deposition chambers.

In accordance with structural aspects of the invention, one exemplaryliner apparatus 30 is shown received within deposition processor chamber18. Such is configured to at least partially restrict at least amajority portion of all internal wall surfaces 19, which definesemiconductor substrate deposition processor chamber 18, from exposureto deposition material within chamber 18. Liner apparatus 30 is depictedas comprising a plurality of pieces 31, 32, 33, 34, 35, 36, 37 and 38.At least some of such pieces are sized for passing completely throughsubstrate passageway 20 to chamber 18 through which semiconductorsubstrates pass into and out of the chamber for deposition processing.In one embodiment, only some of the pieces are, sized for passingcompletely through such passageway, whereas in another embodiment, allof such pieces are sized for passing completely through the passageway.FIG. 2 depicts an embodiment wherein all such pieces are intended todepict sizing for insertion and removal capability through passageway20. FIG. 2 depicts pieces 31, 35, 36, 37 and 38 as being annular,whereas pieces 32, 33 and 34 are depicted as not being annular. In thecontext of this document, “annular” includes any ring-like structure,whether perfectly circular and/or with rounded or angled corners.Further, some of the sized pieces might not be annular, but be shapedfor interconnection into an annular-shaped portion of the apparatus. Forexample and by way of example only, one or more of the respective pieces35, 36, 37 and 38 might constitute two or more partial ring-likesegments which, when connected, form an annular-shaped portion of theapparatus.

By way of example only, the respective pieces of liner apparatus 30 aredepicted as having respective tongue and groove interconnections withone another. Of course, any other interlocking, non-interlocking and/oroverlapping configurations are contemplated.

Gas delivery hardware may or may not be statically or dynamicallyconnected, or otherwise associated, with the process chamber liner tofacilitate gas insertion into the subchamber formed by the liner overthe wafer and wafer heater/carrier/susceptor. Further, the liner profileor shape may be formed in any configuration, for example to optimize gasflow characteristics to the substrate. Further by way of example only,inert purge gas feeds may or may not be configured to purge thesubchamber volume above and/or exterior to the subchamber formed by theliner in the process chamber. The liner apparatus can be made from anyexisting or yet-to-be developed material(s), and can be chosen basedupon process considerations.

The invention contemplates a method of replacing at least a portion of asemiconductor substrate deposition chamber liner essentially independentof the preferred embodiment apparatus just described. One exemplaryimplementation includes removing at least a piece of a depositionchamber liner from a deposition chamber by passing it through apassageway to the deposition chamber through which semiconductorsubstrates pass into and out of the chamber for deposition processing. Areplacement for the removed deposition chamber liner piece is providedinto the chamber by passing the replacement through such passageway.Most preferably, the deposition chamber is maintained at subatmosphericpressure during the removing and the providing of the replacement, andany time therebetween. Even further most preferably, the depositionchamber is maintained at a substantially constant subatmosphericpressure during the removing of the piece and the providing of thereplacement, and any time therebetween. In one methodical embodiment,the deposition chamber liner is comprised of multiple pieces, with allsuch pieces being removed from the deposition chamber and replaced withsubstitutes, all of which pass through the passageway to the depositionchamber through which semiconductor substrates pass into and out of thechamber for deposition processing, for example and by way of exampleonly, the above-described and depicted liner apparatus 30.

By way of example only, one exemplary method of carrying out methodicalaspects of the invention as just so stated is described with referenceto FIGS. 2-4. Such depicts exemplary hardware associated with clusterapparatus 10 which can be utilized for practicing methodical aspects ofthe invention. However, methodical aspects of the invention are in noway limited to utilization of the depicted hardware. Practice of theinvention utilizing any hardware, whether existing or yet-to-bedeveloped, is contemplated in accordance with the methodical aspects ofthe invention, which are to be limited only by the accompanying claimsas literally worded, without limiting or interpretative reference to thespecification, and in accordance with the doctrine of equivalents.

FIGS. 1-3 depict transfer mechanism 16 as having an arm 40 which isextendable to within deposition chamber 18. The operative end of arm 40is diagrammatically depicted as having a pair of opposing prongs/paddles42, 43. Such are depicted for lateral inward and outward movement forengaging at least one piece of a deposition chamber liner withindeposition chamber 18. Prongs/paddles 42, 43 are also depicted as beingmounted at the end of arm 40 for elevational raising (FIG. 4) andlowering (FIG. 5) within deposition chamber 18. Such is onlydiagrammatically illustrated in the form of an overlapping/telescopingmechanism assembly 44 as one possible implementation for effecting thedesired movements for engaging any of the depicted pieces 31-38 of theexemplary liner apparatus 30. Again, any mechanism for inserting atleast one piece of a chamber liner into the chamber is contemplated, forexample whether received within the chamber, a transfer chamber orexternal thereof, and whether man-powered or powered by other means, forexample by electrical, pneumatic, magnetic and any other means ofinciting motion whether existing or yet-to-be developed. Further by wayof example only, the mechanism for providing and inserting the chamberliner into the chamber in an operative position may have many axes ofmovement, non-limiting examples of which include extension, rotation onextension, blade rotation about numerous axes, elevation of blade,elevation of extension, and others.

One exemplary methodical implementation would engage a piece of adeposition chamber liner with an arm extending through a passageway tothe deposition chamber through which semiconductor substrates pass intoand out of the chamber for deposition processing. One exemplary methodof engaging would be to utilize arm 40 and its associated hardware asdepicted in FIGS. 1-5. For example and by way of example only, thedepicted apparatus could be configured as shown in FIG. 4, with arms 42,43 moved radially outwardly internally of piece 31 for bearingengagement thereof. Alternately by way of example only, arms 42, 43could be used to grasp piece 31 by squeezing against opposing outerlateral surfaces thereof. Liner piece 31 could then be lifted upwardlyfrom the liner apparatus assembly 30, as shown in FIG. 4. FIG. 2 depictsliner apparatus 30, and all liner subpieces thereof, received in anoperable lining position within chamber 18 when semiconductor substratesare deposited upon within the chamber. The exemplary described. FIG. 4engaging and lifting effectively displaces chamber liner piece 31 fromsuch lining position by arm mechanism 40.

By way of example only, engaged chamber liner piece 31 could then bemoved laterally in the direction of passageway 20 and elevationallylowered to be proximate thereto. Such provides but one exemplary aspectof moving the engaged chamber liner piece with the arm to proximate suchpassageway. Rotational, pivoting or other movement might be associatedtherewith to accommodate movement of piece 31 to proximate passageway 20for ultimate removal from chamber 18 therethrough. Alternately or inaddition thereto, piece 31 might constitute a plurality of subpieceswhich are separately individually grasped and positioned by an armassembly for ultimate removal from chamber 18 through passageway 20.Regardless, in this example embodiment, the engaged chamber liner pieceis removed from deposition chamber 18 with arm 40 by passing the chamberliner piece through passageway 20. In one embodiment, and as depicted,the passing of the piece through the passageway would be in a firstdirection (i.e., horizontally), wherein the moving of the engagedchamber liner piece with the arm to be proximate the passageway wouldinclude moving in a second direction (i.e., vertically) which isgenerally transverse the first direction.

The above processing could be continued as desired to remove each of thedepicted respective pieces 31-38 from the chamber through passageway 20,and most preferably without exposing chamber 18 to room atmosphericpressure conditions. Regardless, a replacement piece or pieces could beprovided within the chamber by passing the replacement(s) throughpassageway 20 with the arm. Further, the replacements could be movedinto their respective lining positions within chamber 18 forre-establishing a protective lining within the chamber.

The above-described exemplary methodical and apparatus embodimentsbasically depict liner apparatus 30 as essentially comprising afree-standing structure. Any alternate construction is contemplated,however, whether existing or yet-to-be developed. For example and by wayof example only, one or more pieces of a liner apparatus utilized orconstructed in accordance with the invention might be retained ormounted within the chamber by connection with any of the internalchamber walls or subcomponents of the chamber. By way of example only,such might include vacuum retention, mechanical fasteners, magneticretention, pins, mechanical up/down release mechanisms, bayonet-typerotary mounts, sliding bracket mounts, electromagnetic mounts, etc.

FIGS. 6-9 depict one exemplary embodiment whereby a piece of adeposition chamber liner is engaged with a substrate holder receivedwithin the deposition chamber. For example, FIG. 6 depicts chamber linerpiece 31 held and engaged by actuator arms 42, 43 within chamber 18.Referring to FIG. 7, heater/support 24 has been moved upwardly toengagingly support chamber liner piece 31, and arm/actuator 40 has beenremoved from chamber 18.

Referring to FIG. 8, heater/support 24 has been further raised upwardlyto bear chamber liner 31 against the upper surface of chamber 18, and tobe retained thereagainst ultimately by something other than support 24.Again, many manner, whether existing or yet-to-be developed, forretaining chamber liner piece 31 against or otherwise in position withinchamber 18 in FIG. 8 is contemplated.

Referring to FIG. 9, heater/support 24 has been lowered.

A method of replacing piece 31 would include engaging it withsemiconductor substrate holder 24 within deposition chamber 18, forexample as shown in FIG. 8. Through release of uplocks or othermechanisms or means, either by movement or engagement with heater 24 orotherwise, piece 31 is released or otherwise initially moved/displacedfrom its FIGS. 8 and 9 depicted operational lining position. The engagedchamber liner piece is then moved with semiconductor substrate holder 24to proximate passageway 20. Chamber liner piece 31 can then be removedfrom deposition chamber 18 by passing it through passageway 20, forexample utilizing the arm effectors as shown in FIG. 6. Again,replacement therefore can be provided as initially described above.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method of replacing at least a portion of asemiconductor substrate deposition chamber liner comprising: removing atleast a piece of a deposition chamber liner from a deposition chamber bypassing it through a passageway to the deposition chamber through whichsemiconductor substrates pass into and out of the chamber for depositionprocessing; and providing a replacement for the removed depositionchamber liner piece into the chamber by passing the replacement throughsaid passageway through which semiconductor substrates pass into and outof the chamber for deposition processing.
 2. The method of claim 1wherein the deposition chamber is maintained at subatmospheric pressureduring the removing and the providing, and between the removing and theproviding.
 3. The method of claim 1 wherein the deposition chamber ismaintained at a substantially constant subatmospheric pressure duringthe removing and the providing, and between the removing and theproviding.
 4. The method of claim 1 wherein the chamber liner piece isannular.
 5. The method of claim 1 wherein the deposition chamber lineris comprised of multiple pieces, and comprising removing and replacingall said pieces through said passageway.
 6. The method of claim 1wherein the passageway includes a maximum height of no greater than 0.75inch and a maximum width of no greater than 8.25 inches.
 7. The methodof claim 1 wherein the passageway includes a maximum height of greaterthan 0.75 inch and a maximum width of greater than 8.25 inches.
 8. Amethod of replacing at least a portion of a semiconductor substratedeposition chamber liner comprising: engaging a piece of a depositionchamber liner with a semiconductor substrate holder within a depositionchamber; moving the engaged chamber liner piece with the semiconductorsubstrate holder to proximate a passageway to the deposition chamberthrough which semiconductor substrates pass into and out of the chamberfor deposition processing; removing the chamber liner piece from thedeposition chamber by passing it through the passageway; and providing areplacement for the removed deposition chamber liner piece into thechamber by passing the replacement through said passageway through whichsemiconductor substrates pass into and out of the chamber for depositionprocessing.
 9. The method of claim 8 wherein the removing comprisesengaging the chamber liner piece with an arm extending through thepassageway, and by passing the chamber liner piece through thepassageway with the arm.
 10. The method of claim 8 wherein the chamberliner piece is annular.
 11. The method of claim 8 wherein the depositionchamber is maintained at subatmospheric pressure during the removing andthe providing, and between the removing and the providing.
 12. Themethod of claim 8 wherein the deposition chamber is maintained at asubstantially constant subatmospheric pressure during the removing andthe providing, and between the removing and the providing.
 13. Themethod of claim 8 wherein the deposition chamber liner is comprised ofmultiple pieces, and comprising removing and replacing all said piecesthrough said passageway.
 14. A method of replacing at least a portion ofa semiconductor substrate deposition chamber liner comprising: engaginga piece of a deposition chamber liner with an arm extending through apassageway to the deposition chamber through which semiconductorsubstrates pass into and out of the chamber for deposition processing;moving the engaged chamber liner piece with the arm to proximate saidpassageway; removing the chamber liner piece from the deposition chamberwith the arm by passing the chamber liner piece through the passageway;and providing a replacement for the removed deposition chamber linerpiece into the chamber by passing the replacement through saidpassageway with the arm.
 15. The method of claim 14 wherein the engagingdisplaces the chamber liner piece from a lining position within thechamber in which the chamber liner piece is received when semiconductorsubstrates are deposited upon within the chamber.
 16. The method ofclaim 14 comprising prior to the engaging, displacing the chamber linerpiece from a lining position within the chamber in which the chamberliner piece is received when semiconductor substrates are deposited uponwithin the chamber with something other than an arm extending throughthe passageway.
 17. The method of claim 14 wherein the passing is in afirst direction, the moving including movement of the chamber linerpiece in a second direction generally transverse the first direction.18. The method of claim 14 comprising after the providing, moving thereplacement into a lining position within the chamber in which thechamber liner piece was received when semiconductor substrates aredeposited upon within the chamber.
 19. The method of claim 14 whereinthe deposition chamber is maintained at subatmospheric pressure duringthe removing and the providing, and between the removing and theproviding.
 20. The method of claim 14 wherein the deposition chamber ismaintained at a substantially constant subatmospheric pressure duringthe removing and the providing, and between the removing and theproviding.
 21. The method of claim 14 wherein the deposition chamberliner is comprised of multiple pieces, and comprising removing andreplacing all said pieces through said passageway with the arm.
 22. Amethod of depositing materials over a plurality of semiconductorsubstrates, comprising: providing a subatmospheric deposition chamber incommunication with a subatmospheric transfer chamber; processing a firstplurality of semiconductor substrates within the subatmosphericdeposition chamber effective to deposit one or more materials over saidfirst plurality, said first plurality of substrates passing from thesubatmospheric transfer chamber to the subatmospheric deposition chamberand then from the subatmospheric deposition chamber to thesubatmospheric transfer chamber through a substrate passagewaytherebetween; after processing the first plurality of substrates,removing at least a piece of a chamber liner received within thesubatmospheric deposition chamber by passing it through the substratepassageway into the transfer chamber; providing a replacement for theremoved deposition chamber liner piece into the subatmosphericdeposition chamber by passing the replacement from the subatmospherictransfer chamber through the substrate passageway into thesubatmospheric deposition chamber; and processing a second plurality ofsemiconductor substrates within the subatmospheric deposition chambereffective to deposit said one or more materials over said secondplurality; all of said first plurality processing, said removing, saidproviding a replacement and said second plurality processing occurringwithout exposing either the transfer chamber or the deposition chamberto room atmospheric pressure.
 23. The method of claim 22 wherein thefirst and second plurality processings are one substrate at a time. 24.The method of claim 22 wherein the deposition chamber is maintained at asubstantially constant subatmospheric pressure during said all.
 25. Themethod of claim 22 wherein the chamber liner piece is annular.
 26. Themethod of claim 22 wherein the deposition chamber liner is comprised ofmultiple pieces, and comprising removing and replacing all said piecesthrough said passageway intermediate the first plurality processing andthe second plurality processing.
 27. The method of claim 22 wherein thepassageway includes a maximum height of no greater 0.75 inch and amaximum width of no greater than 8.25 inches.
 28. The method of claim 22wherein the passageway includes a maximum height of greater than 0.75inch and a maximum width of greater than 8.25 inches.